1. Field of the Discovery
The present disclosure relates to asphalt and aggregate compositions and methods of using the same for coating roads, parking lots, and other driving surfaces.
2. Background
It is well known that, for asphalt pavements, a preventative maintenance treatment (typically an asphalt coating composition referred to as a “sealer”) will commonly be applied to the paving surface every 2-5 years or so. The coating material will typically be comprised of liquid asphalt or an anionic asphalt emulsion and will be applied, e.g., using a wand sprayer or a spraying machine. The coating desirably operates to (a) seal the surface from water intrusion, (b) improve the appearance of the pavement, (c) protect the underlying asphalt pavement from oxidation and UV damage, (d) protect the pavement from oil and gasoline spills, and (e) provide a surface which is easier to sweep, clean, shovel, and maintain. All of these benefits increase the service life of the pavement.
Unfortunately, after curing, the micro-texture of the asphalt coatings heretofore known in the art has been much smoother than the micro-texture of the underlying pavement surface so that the frictional resistance offered by the asphalt coating has been significantly less than that of the underlying pavement. This reduction in frictional resistance is not a concern in low speed environments. However, because of this significant loss in surface frictional resistance, asphalt maintenance coatings of this type have not been applied to asphalt road surfaces or to other asphalt paving surfaces upon which vehicles will be traveling at higher speeds.
Typical sealers are not formulated with a viscosity to suspend the aggregates chosen to enhance friction in other typical paving applications. The frictional aggregates used in other applications derive their frictional characteristics from both larger particles which cannot be sprayed, and from material properties chosen with a maximum value of hardness and density. Additionally, conventional slurry seal (SS) and micro-surfacing (MS) treatments require mixing at the time of application, which is associated with higher costs for application.
Consequently, a need exists for an improved asphalt and aggregate coating composition, including sprayable forms, which (a) will provide an increase in the degree of surface micro-texture roughness when cured, (b) preferably will not have a lower surface micro-texture roughness than the underlying pavement to which it is applied, (c) can be applied using conventional equipment, (d) will be highly durable, (e) will provide improved micro-texture over the life of the spray coating, (f) will provide all of the other benefits of a superior pavement coating, and (g) can be pre-mixed, stored, and transported for later use.